Unit 11

• Lateral border – anterior border of the sternocleidomastoid
• Superior border – inferior border of the mandible
• Medial border – midline of the neck
• Inferior border – manubrium

• Submental
• Submandibular – salivary glands
• Carotid – carotid sheath, common carotid,internal jugular vein, & vagus nerve
• Muscular – infrahyoid muscles

• Superior border – inferior border of the mandible
• Inferior border – anterior and posterior belliesof the digastric muscle

• Inferior border – hyoid bone
• Lateral border – anterior belly of the digastric muscle
• Medial border – midline

• Superior border – hyoid bone
• Lateral border – superior belly of the omohyoid & anterior border of the sternocleidomastoid muscle
• Medial border – midline

• Anterioinferior border – superior belly of the omohyoid muscle
• Superior border – stylohyoid muscle & posterior belly of the digastric muscle
• Posterior border – anterior border of thesternocleidomastoid muscle

• The hyoid bone is a small U-shaped bone orientedin the horizontal plane just superior to the larynx, where is can be palpatedand moved form side to side.
• The hyoid bone does not articulate directly with any other skeletal elements in the head or neck.
• The hyoid bone is a highlymovable and strong bony anchor for a number of muscles and soft tissue structures in the head and neck

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• The body of hyoid bone is anterior and forms the base of the U.
• The two arms of the U (greater horns or cornu) project posteriorly form the lateral ends of the body

Thyroid cartilage – which is really prominentanteriorly and forms a C shape structure

Cricoid cartilage – which is the only completecircular cartilage around the airway

Thyroid gland – which is an endocrine gland that is positioned anteriorly in the neck. It is a large, unpaired gland, whichconsists of two lateral lobes (which cover the anterolateral surfaces of thetrachea, the cricoid cartilage, and the lower part of the thyroid cartilage)with an isthmus that connects the lateral lobes and crosses the anteriorsurfaces of the second and third tracheal cartilages.

• Eight muscles articulate on the hyoid bone.
• Four suprahyoid muscles.
• Four infrahyoid muscles.

• The four pairs of suprahyoid muscles are in the submental and submandibular triangles. They pass in a superior direction formthe hyoid bone to the skull of mandible and raise the hyoid, as occurs during swallowing
• Stylohyoid. Digastric. Mylohyoid. Geniohyoid.

• The four infrahyoid muscles are in the muscular triangle. They attach the hyoid bone to inferior structures and depress thehyoid bone. They also provide a stable point of attachment for the suprahyoid muscles.
• Sternohyoid. Omohyoid. Thyrohyoid.Sternothyroid.

• Origin: base of styloid process
• Insertion: lateral area of body of hyoid bone
• Innervation: Facial nerve (CN7)
• Function: pulls hyoid bone upward in aposterosuperior direction

• Origin: [anterior belly]: digastric fossa onlower inside of mandible; [posterior belly]: mastoid notch on medial side ofmastoid process of temporal bone
• Insertion: attachment of tendon between two bellies to body of hyoid bone
• Innervation: [anterior belly]: mylohyoid nerve from inferior alveolar branch of mandibular nerve (V3)[CN5];[posterior belly]: Facial nerve (CN7)
• Function: [anterior belly]: opens mouth by lowering mandible; raises hyoid bone [posterior belly]: pulls hyoid bone upward and back

• Origin: mylohyoid line one mandible
• Insertion: body of hyoid bone and fibers from muscle on opposite side
• Innervation: mylohyoid nerve from inferior alveolar branch of mandibular nerve (V3) [CN5]
• Function: support and elevation of floor of mouth; elevation of hyoid

• Origin: inferior mental spine on inner surface of mandible
• Insertion: anterior surface of body of hyoid bone
• Innervation: branch form anterior ramus of C1(carried along the hypoglossal nerve [CN12])
• Function: fixed mandible elevates and pulls hyoid bone foreword; fixed hyoid bone pulls mandible downward and inward

• Origin: posterior aspect of sternoclavicularjoint and adjacent manubrium of sternum
• Insertion: body of hyoid bone medial to attachment of omohyoid muscle
• Innervation: anterior rami C1 to C3 through the ansa cervicalis
• Function: depresses hyoid bone after swallowing

• Origin: superior border of scapula medial to suprascapular notch
• Insertion: lower border of body of hyoid bone just lateral to attachment of sternohyoid
• Innervation: anterior rami C1 to C3 through the ansa cervicalis
• Function: depresses and fixes hyoid bone

• Origin: oblique line on lamina of thyroid cartilage
• Insertion: greater horn and adjacent aspect of body of hyoid bone
• Innervation: fibers form anterior ramus of C1carried along hypoglossal verve [CN12])
• Function: depresses hyoid bone, but when hyoid bone is fixed raises larynx

• Origin: posterior surface of manubrium of sternum
• Insertion: oblique line on lamina of thyroid cartilage
• Innervation: anterior rami C1 to C3 through the ansa cervicalis
• Function: draws larynx (thyroid cartilage) downward

• C1 – hitchhiking on hypoglossal n. – thyrohyoid & geniohyoid muscles (tongue) descendens hypoglossi (superior root) –superior belly of omohyoiod muscle
• C2 & C3 – descendens cervalis (inferior root) sternohyoid sternothroid & inferior belly of omohyoid

It splits into the internal and external carotid arteries

• Superiorthyroid, Ascending pharyngeal, Lingual, Facial, Occipital, Post Auricular, Superficial temporal, Maxillary
• [Some Anatomists Like Fucking, Others Prefer S& M]

• The lingual artery runs deep to the hyoglossus muscle
• The facial artery runs superficial to the hyoglossus muscle and the submandibular gland and will eventually supply bloodto the face
• The lingual nerve is going to run deep to the mylohyoid but superficial the hyoglossus

The retromandibular vein is formed in the substance of the parotid gland when the superficial temporal and maxillaryveins join together, and pass inferiorly in the substance of the parotid gland.It usually divides into anterior and posterior branches just below the inferior border of the gland.

• Superior laryngeal nerve
• Pharyngeal nerve
• Recurrent laryngeal nerve

Internal branch & external branch

• Internal laryngeal branch runs through the thyrohyoid membrane with the superior laryngeal artery
• This branch innervates the internal aspects of the superior larynx

External laryngeal branch runs into the criothyroid muscle, which attaches from the cricoid cartilage to the thyroidcartilage. This muscle helps to change the shape of the larynx.

• This nerve innervates the inferior portion of the larynx
• On the left, the nerve loops under the arch of the aorta then continues running up between the trachea and the esophagus. However, on the right, it loops around the right subclavian artery then continues running up between the trachea and the esophagus

Superior cervical sympathetic ganglion, middle cervical sympathetic ganglion, and cervicothoracic (stellate) ganglion[superior to inferior]

• There are located in the submandibular region
• There are three salivary glands within the submandibular region: submandibular, parotid, and sublingual gland

• It is located partially in the submandibular triangle and partially in the mouth
• It wraps around the mylohyoid muscle
• The gland produces saliva in order to break down food. This saliva travels through the submandibular duct to reach the mouth
• The lingual nerve starts out superior andlateral to the submandibular duct and ends up inferior and medial [SLIM] to the duct

This gland is located deep and medial to the ear.

This gland is located underneath the tongue in the mouth

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• The thyroid gland has 2 lateral lobes connected by an isthmus across tracheal ring 2-4
• Pyramidal lobe variably present

Thyroid gland is an endocrine gland that secretes thyroxin which is important for metabolism

Embedded into the posterior aspect of the gland are 2 to 6 small parathyroid gland which secrete parathyroid hormone forcalcium homeostatasis

Superior thyroid and inferior thyroid veins and arteries [two major blood sources]

The nerve runs deep to the gland. If it is damaged through surgery, the individual will become horse.